The inventions described herein may be manufactured and used by or for the U.S. Government for U.S. Government purposes.
This invention relates generally to hand-held impact devices, and more particularly to hand-held impact devices for gaining entry to locked or barricaded structures.
There is often a need for authorized personnel to rapidly gain access to locked, barricaded or otherwise secured buildings and to damaged structures, particularly in response to illegal activity or an emergency. Portable, hand-held forcible entry devices have been developed that enable law enforcement and emergency personnel to forcibly open a locked or fortified door, barricaded passage, damaged structure, or any other barrier that requires the use of force to gain access to a building or structure.
A typical forcible entry device comprises a piston-driven striker housed within a generally cylindrical case. The end of the striker extends from the front end of the case. A modified, conventional firearm is secured to the other end of the case for discharging the forcible entry device. The modified firearm fires a blank cartridge or other explosive charge which generates a combustion gas for driving the piston-driven striker outwardly of the housing to produce an extreme percussive force. In use, the striker is placed against a target object, such as a locked or barricaded door or damaged structure, and the firearm is fired. The striker extends from the front end of the case with great force and impacts the target object for breaking through the door or structure.
A problem with conventional forcible entry devices is the recoil generated when the device is fired due to the large force necessary to drive the striker. The recoil makes the device difficult for the user to hold and to control in use. Another problem with using forcible entry devices occurs when the target object offers little resistance to the striker. The force generated by the high velocity extension of the striker results in xe2x80x9cforwardxe2x80x9d recoil wherein the device jerks forward in the user""s hands. Forward recoil is also a problem when the devices are xe2x80x9cdry firedxe2x80x9d, that is, fired when the striker does not impact a target object.
For the foregoing reasons, there is a need for a new impact generating device for use in forcible entry of locked or damaged structure which is recoilless. The new device should be recoilless in the traditional sense and minimize forward recoil in the case of soft target objects or dry firing. Ideally, the new impact device should also be compact and lightweight, and thus portable enough to be rapidly positioned and deployed to gain access to a structure without the need for an external power source.
Therefore, it is an object of the present invention to provide an impact generating device which is recoilless.
Another object of the present invention is to provide an impact generating device which minimizes forward recoil, even when impacting soft target objects or when dry fired.
A further object of the present invention is to provide a recoilless impact generating device which is useful in forcible entry of a locked or damaged structure.
According to the present invention, an apparatus for generating an impact against a target object comprises a housing defining an interior chamber and having a closed first end and an open second end. A drive member is reciprocally disposed in the interior chamber adjacent the second end of the housing for movement relative to the housing from a first firing position to a second driven position. The drive member includes a hollow tube member having a first closed end and a second open end. A nozzle member having a plurality of openings is sealably mounted in the second end of the tube. A piston is disposed in the tube for movement relative to the tube and propellant is disposed between the piston and the closed end of the tube. Fluid is also in the tube between the nozzle member and the piston. Means are provided for sealing the openings in the nozzle member, wherein the nozzle opening sealing means is adapted to rupture when the pressure in the tube exceeds a predetermined pressure. A striker member having a head portion and a shaft portion is mounted within the interior chamber so that in a first retracted position of the striker member the head portion of the striker member is proximate the drive member and a portion of the shaft portion extends outwardly from the interior chamber through a passage formed in the closed end of the housing. The striker member is movable relative to the housing between the first position and a second extended position where the head portion is adjacent the first end of the housing. Means are provided for igniting the propellant so that combustion gases build pressure in the tube member between the piston and the closed end of the tube member causing the pressure in the tube member to exceed the predetermined pressure for rupturing the nozzle sealing means. This causes the piston to move toward the nozzle member and fluid to be expelled through the nozzle member for moving the drive member against the head portion of the striker member and to the driven position. The drive member transfers energy to the striker member for moving the striker member to the second position at high velocity for driving the end of the striker with great force against the target object. Recoil action in the apparatus is cushioned by the fluid exiting the tube member through the nozzle member as the piston moves toward the nozzle member.